Thermapen Instant Read Thermometer
02/08/14 - 16:06 Filed in: Thermometers | Gear | Review
This blog discusses my first impressions and what I have learned so far about the Splash-Proof ThermoWorks Super-Fast Thermapen instant read thermometer. This is the thermometer of choice for many chefs and others in the food service industry and serious non-professional cooks. I was always a bit skeptical due to the high price of this model ($96.00), but even after a short time using it I am a convert. I will attempt to explain why this thermometer is worth every penny, in a way that a skeptic like myself will understand.
A benefit to all of the overtime hours I put in this past fall was having some extra spending money around to devote to getting some cool tools for my grill. I have owned two fast instant read thermometers which were in the same price range, but they were combo units where they were infra-red/instant read thermometers. I bought these thermometers for their fast instant read capabilities, with the infra red being an afterthought for me. I soon found out I actually valued the infra red capabilities too. The bottom line here though is even though these two thermometers cost about as much as the Thermapen, they were trying to do two different jobs for the same price. The Thermapen was a one-trick pony, but it was a very good trick. There is an old saying: When you buy an expensive tool you’ll regret it only once, when you buy it. When you buy a cheap tool you’ll regret it every time you use it. The moment I took a serious look at the Thermapen I could tell it was a quality product. I am not just talking about the specs, I am talking about the build quality too. This is not the typical mass market, made in China cheap device. It is made and hand assembled in England. Too many issues with cheaply made Asian products have taught me that the extra money paid for a quality built product is well worth it. When I started actually using it, I noticed a difference right away too.
IT’S ALL ABOUT THE PROBE: The probe of the Thermapen is what sets it apart from other cheaper thermometers. The business end of the probe uses a sensor called a thermocouple. It is the type of sensor used for measuring food temperatures in professional kitchens. The cheaper “instant” read thermometers use a sensor called a thermistor. These are very cheap to manufacture, and somewhat fast to respond but an accurate reading does take longer. So sometimes the “Instant Read” moniker is referring to the response time, not the accuracy of those initial readings. What makes the thermocouple type thermometer more expensive is the electronics needed to convert the readings from the probe to an actual temperature reading. The ThermoWorks Company claims to have found a way to reduce the cost (and size) of the circuit board & electronics so they can make an “affordable” (if you call $96.00 affordable) thermocouple based thermometer. Many other thermocouple type thermometers sell for $150-$200. ThermoWorks also claims the Thermapen is as accurate as these other more costly thermocouple type thermometers. I tend to believe them because the other claims they have made about the specs for the Thermapen have proven true in third party testing.
SPECS: An instant read thermometer’s raison d’être is to take fast accurate readings of your food. The specs are impressive. The temperature reading is said to be accurate within +/- 0.7 degrees F (0.4C). You get a ballpark reading within 1 second and a full accuracy reading within 3 seconds. The two infra-red/instant read models I owned prior to this were said to be accurate to within +/- 1.4 or 1.8 degrees. So the Thermapen has half the amount of temperature variation. These thermometers claimed to get a reading that was 90 percent accurate within 1 second. They didn’t give a final time to an accurate reading. Even after a few uses I had a gut feeling the Thermapen was faster with an initial reading and got you to within the ballpark way faster. I finally decided to try some unscientific testing just to see if what I noticed was a measurable difference, or just me “wanting” it to be faster to help justify the expense.
TESTING 1,2,3: I filled two identical pint sized glasses (16 oz. / 470ml) with water. One I filled an hour early and let get to room temperature. The other I filled with as much ice as I could and added the coldest tap water I could draw from the faucet. I used the stop watch on my iPhone to measure the approximate times. I would start the stop watch and when it hit 10 seconds I would have the thermometer entering the water. I didn’t bother timing the first insertion into the room temperature water, because the thermometers were both at that temperature from measuring the air temperature. Both thermometers said the room temperature water was 73 degrees, but what happened next proved to me I wasn’t imagining things. The Bonjour Laser Probe went from 73 (22.8C) to a reading of 55F (12.8C) in the blink of an eye and the reading was on screen just long enough to register with me. Then it jumped down to 43 degrees (6.1C) in about one second. The readings continued downward in 1 or 2 degree increments. It took it another 10 seconds to settle on a reading of 35 degrees (1.6C). The Thermapen read 42 degrees (5.6C) for a split second and then jumped down to 36 degrees (2.2C) within the approximately one second time frame. Within another second or so it got down to 34 degrees (1.1C). At this point I was prepared to buy the 3 seconds claim, but then something interesting started happening. The readings were jumping up and down in 1 or 2 degree increments. My initial thought was that the readings hadn’t settled in on the final temperature and the 3 second claim might be a little ambitious. On closer inspection I noticed what was going on. I was not keeping the probe in the exact same place. My hand was moving slightly and the fluctuating temperature readings reflected this. Sometimes the probe was in the water, sometimes it was touching a piece of ice. When I steadied my hand, the readings settled down immediately.
I tried this test three more times, taking care to keep my hand steady. When going back to the 73 degree (22.8C) water the Thermapen went from 34 (1.1C) to 73 (22.8) in one quick direct jump of about one second. Once it went to 71 (21.7C) to 73 (22.8C) in just over a second. The Bonjour went to a reading of around 66 (18.9C) degrees and then rose in 1 to 2 degree intervals and took about six seconds to get there. So my quasi-scientific testing proved to my satisfaction that the speed difference I noticed wasn’t wishful thinking on my part. It also showed me that the Thermapen claims were valid claims and the Bonjour claims were a bit optimistic.
CLAIM CHOWDER: On the ice water test the Bonjour showed 43 (6.1C) degrees after 1 second, or an 8 degree variation from its final reading of 35 degrees (1.6C). This is a 22% deviation or 78%, not 90% accuracy. In the other direction it was 91 percent accurate. After 1 second had elapsed, the Thermapen’s reading was 94 percent accurate going into the cold water and was 100 percent accurate going to the room temperature water. They never made a claim for the precise amount of accuracy, they just said ballpark reading after 1 second, accurate reading after 3 seconds. Even without making any claim, the Thermapen did better than the claims made by the Bonjour model. The Bonjour model missed their 90 percent accuracy within 1 seconds claim going from room temperature water, managing only 78% accuracy. My Thermapen came with a certificate with a serial number showing it had passed standard’s based testing procedures and met the accuracy claims of the manufacturer. Also I had done some investigation online and had seen YouTube videos testing the Thermapen or read reports online that backed up the claims of the ThermoWorks Company. So I never doubted their claims. My testing was more to see how the well the Bonjour thermometer did, and if my initial perception it was somewhat slower was fact or wishful thinking.
The sensor for the Thermapen is actually in the tip of the tip. It is a micro thermocouple which allowed the tip to be smaller than the typical thermometer. Even the main shaft of the Thermapen is thinner.
GET TO THE POINT: I mentioned earlier that the sensor was what helped set the Thermapen apart. This sensor also is more compact than the thermistor type sensor. ThermoWorks calls it a micro-thermocouple sensor. This has a big effect on the shape of the tip of the probe and the size of the probe itself. The first 1/2” (1.3cm) of the probe is less than 1/16” (1.6mm) in diameter. The probe then flares out and widens to approximately 3/32” (2.4mm) in diameter for the remaining 4” (10cm) of the shaft. The sensor is in the very tip of the probe and it is said you can measure foods that are as little as 1/4” (6.3mm) thick. The sensor of a thermistor type device is bigger and cannot be squeezed into a tiny tip. In fact it can’t be squeezed into the tip at all. The sensor is in the main body of the shaft of the probe, which is around 1/8” (3.2mm) in diameter. Unlike the Thermapen which is taking it’s readings at the very tip, the probe of thermistor device is higher up in the shaft. This requires the readings be taken anywhere from 1/2” to 1” (1.27cm-2.54cm) above the tip. This precludes you from using this type of probe on thin food. Also the thinner probe for the Thermapen is easier to insert due to the smaller diameter of the probe and you don’t have to go quite as deep into the food to get an accurate reading. You are also leaving smaller holes in your food and loosing less juice by doing so.
BUILD QUALITY: The newest Thermapen is now called splash-proof. While you can’t immerse it in water and expect it to live, it should easily survive having some liquids splashed on it or getting a little rain on it while taking a reading outside. When I was in my tire-kicking stage I looked at an assembly video on the Thermapen website and I was very impressed with what I saw. The unit is thoroughly protected from moisture in multiple ways. The first line of protection is the black band that wraps completely around the sides of the body. This band felt like a hard rubber-like material of some sort and it turns out it is a gasket. There is a continuous slot along the top and bottom of this gasket that flanges on the two plastic body halves fit into. There is a second line of defense inside the area containing the hinge which allows the probe to pivot out in an up to 180 degree arc. This round compartment for the hinge area is isolated from the compartment holding the electronics. There is a round gasket inside this round compartment to create a good moisture seal. A piece of the gasket is slotted where the probe wire passes through. There is a rubber grommet that fits into the slot in the gasket. This grommet holds the probe wire in the slot and helps seal the area where the probe wire enters the main body of the thermometer. The third line and final line of defense is a piece of silica gel (a desiccant that absorbs moisture) which is secured inside the main body of the thermometer where the sensor electronics are located. The electronic circuit board receives a stick on label with a serial number. It is peeled from the teat result label sent to the end user. This is the label showing the circuit board passed all tests and it bears the same serial number as the label stuck onto the board. The battery compartment cover is threaded and screws in. This also helps keep the moisture out. The two halves of the body are screwed together using 6 screws which are installed with a torque screwdriver. A label then goes on the back side of the unit covering the heads of the countersunk screws. This also help keep water out and keeps food from collecting on top of the screw heads.
MY WORLD: While this falls into the totally non-essential category for me, the Thermapen is available in 15 solid colors as well as some limited edition custom graphics model. For me it is a nice touch, no more. I got mine in Purple, which happens to be my favorite color, but any color would have been fine. The original intent for the colors was to correspond to color coding used in the food service industry for different food types. This way you would use the thermometer of a given color for a certain food group only. By using a set of tools such as cutting boards, knives and thermometers for one food group, say poultry, and another for salad prep you lessen the chance of cross-contamination. I have read that one of the biggest sources of cross contamination is someone cutting up raw chicken for a salad and then using the same knife to cut up the veggies for that salad. There is a chart on the ThermoWorks website showing the color codes. Another use for the colors in the food service industry is when people working in the same kitchen have a unique color Thermapen, so everyone can tell their thermometers apart. Since the initial release of colors, ThermoWorks has released models in additional colors. They also make limited edition Thermapens with graphics such as flags, or camouflage colors, or leopard skin.
The available solid color standard models currently are:
Grey, Black, White, Red, Orange, Yellow, Green, British Racing Green, Teal, Blue, Cornflower Blue, Purple, Pink, Brown, & Tan.
SOME OTHER CONSIDERATIONS:
The LCD for the Thermapen feature characters which are 4x the size of my other thermometers, This makes it easier to read than my other thermometers, for which I need to have my reading glasses to see clearly.
LARGE EASY TO READ DISPLAY: The numbers are on an LCD display using easy to read 0.55” (14mm) characters. Contrast this to my other two instant read thermometers where the numbers are around 1/8” (3.2mm) high. These are impossible to read without glasses and I really don’t want to have to bring my reading glasses out to the grill. The display can be set to read in Fahrenheit or Celsius. You can also turn off the display of decimal degrees if the constantly changing numbers bother you. Additionally you can turn off the feature where the thermometer automatically powers down to help conserve battery life. All of these settings changes are done by accessing the battery compartment.
DISPLAY IS NOT BACKLIT: At first I was surprised to see this and thought it was an across the board negative. For me it was not a negative because I now have my permanent grill lights. The more I thought about it, I decided for the typical buyer of a Thermapen this probably is a non-issue. The typical buyers are going to be professional or advanced amateurs who are going to want to be cooking under adequate lighting. The Thermapen appeals to people sharing our hobby because it allows you to take a quick reading and get the lid closed before you lose the heat. Plus you are most likely going to have enough light to grill by that you will be able to read the large characters on the LCD display. Not having a backlit display certainly helps with the battery life.
LONG BATTERY LIFE: The Thermapen uses two CR2032 3V Lithium batteries. The battery compartment is accessed by unscrewing a round cover. Unlike my other thermometers, the seam around this cover was very fine and the fit was flush with the main body. There is a slot in the cover sized for a coin to use to unscrew the cover. ThermoWorks claims 1,500 hours of battery life. I have no way of confirming this, but I do have some friends that have owned their Thermapens for a number of years, use them all of the time and are still on their original set of batteries.
The Thermapen bears and NSF approved stamp, meaning it is approved for use in professional food service establishments that serve food to the public. It also meats standards for performance and cleanability.
NSF APPROVED: The National Sanitation Foundation Food Safety Division certifies foodservice equipment and has standards for performance, usage and particularly ease of keeping clean. They also have guidelines for foodservice establishments. Many jurisdictions require that the foodservice equipment used to serve food to the public bear the approval stamp showing it has been tested and certified by the NSF. With it’s origins in the foodservice industry, it came as no surprise to me that the Thermapen was NSF approved. In fact I expected it.
The build quality of the Thermapen is a quality level you don’t normally see these days. Notice the tight fit and finish where the clear cover for the LCD fits into the main body of the thermometer. This tight fit helps keep food from building up on the surface of the thermometer.
EASY TO CLEAN: I mentioned that part of NSF approval involves how easy an item is to clean and keep clean. This includes the materials used to make the product and the construction of the device. Fit and finish are very important. Looking at the Thermapen you can tell right away that it is going to be easy to clean and does not have lots of areas which will trap food. The side gasket has an amazingly tight fit and is pretty much flush and for all intents and purposes seamless. The clear plastic over the LCD display fits into the main body of the thermometer perfectly. It is once again flush and seamless. There are no buttons on the body. To turn the Thermapen on you swing the probe out away from the body. After a certain amount of time it turns off automatically or swinging the probe back into the clip in the gasket on the side of the body turns it off. The Bonjour has 4 buttons, many seams, a battery compartment with decent sized gaps all around it full perimeter and a trigger which a large gap around the base where it enters into the body of the thermometer. All of these areas can trap food and be difficult to clean. This thermometer is not NSF certified and it is easy to tell why.
POCKET SIZED: Many thermometers using thermocouple technology are quite a bit larger than the Thermapen. The Thermapen model has the micro thermocouple sensor and the electronics board is a reduced size. This allowed the ThermoWorks company to make a model which can be slipped into a pocket.
CALIBRATION CERTIFICATE: Each thermometer is factory calibrated and the certificate is in the box. Unlike a classic thermometer where a liquid rises a given amount at a given temperature, the process for a digital thermometer is different. These type of sensors and electronics are actually set during testing to achieve the correct reading. They are inserted into a container of water at boiling temperature and the electronics are tuned so the LCD shows this reading. They are inserted into ice water etc. After the thermometer electronics are calibrated to achieve correct readings at the test temperature used, they are tested again to make sure the readings are repeatable. At this point the certificate is generated with a unique serial number and it is packaged together with the probe & circuit board in a foil bag and sent on for final assembly. During final assembly a portion of this certificate, which is a peel and stick label with a copy of this serial number on it, is placed on the back of the circuit board before the board is installed inside the thermometer. In this way the circuit board can be matched with it’s test results. After assembly the thermometer is set on for final testing to insure it has maintained it’s accuracy.
NICE TOUCH: A final totally non-essential nice-touch was the pack of Jelly Bellys a well known brand of jelly beans made in Britain. There was a Jelly Belly in each of the colors that the Thermapen comes in. If I am any example the strategy is memorable and pays off: I don't even like jelly beans and here I am writing about it. I’m sure more than one conversation about the Thermapen has been started by someone mentioning they got a new thermometer that came with a pack of jelly beans.
USING THE THERMAPEN: I am going to finish off describing the Thermapen in use. Other than pulling the probe away from the body, everything is a one-handed use. You grab the probe and pull it out of the clip built into the side gasket and rotate the probe away from the body which turns on the Thermapen. The probe can be swung out up to 180 degrees. The way I use my Thermapen may be a little different than some folks. I generally use a remote read thermometer whenever I can and the remote read Thermometer comes into use when the remote read tells me I am getting close to my desired end temp. So I use the remote less than some, but when I do use it I am at critical point in the cook.
I mentioned at the beginning that I felt the Thermapen was somewhat faster that the other fast instant read thermometers I’ve owned. It seemed to jump into the ballpark temperature and settle in on a final temp more quickly. This has changed how I take my readings. I know that the Thermapen is quite close to the mark within the first second. By the time I have the probe situated where I want it in the meat, I generally have an accurate reading. If the Thermapen is much lower than the probe this tells me my probe isn’t really positioned in the center of the meat. I need to reposition the probe. Normally this is NOT the case and the Thermapen is in general agreement with the remote read thermometer. Since I can read the temperature faster, I am taking several readings now because I can do three readings in about the same time I used to do one with the other thermometers. Multiple readings gives you a much better idea of what is really going on in your meat and lets you really hit your target temp. Where the Big Green Egg recovers fast, it doesn’t matter too much if the multiple readings take slightly longer.
The thinner probe, both at the tip and the shaft, is easier to insert into most foods. This speeds up taking readings somewhat too. You just need to remember not to insert the probe quite as deep, because the temperature is measured at the tip not 1” (2.5cm) up the shaft like most probes. I also want to start taking advantage of the Thermapen’s ability to measure temps in food as thin as 1/4” (6.4mm) because this ability was totally not available prior to this. My remote read probes really can’t be used in any food thinner than 1” (2.5cm) and even then I have to insert the probe from the side of the food which is not always the easiest thing to do.
To wrap things up, let me say I am thrilled to have my Thermapen. It is one of these times where you don’t appreciate just how good something is, until you actually have one. In my case I had a couple of instant read thermometers I thought were pretty good. The first time I used my new Thermapen I noticed a difference. You will never regret purchasing a Thermapen and like me, you may start asking yourself why you didn’t get one sooner.
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